Isidore \i-sido-re, is(i)-dore\ as a boy's name is of Greek origin, and the meaning of Isidore is "gift of Isis". Isis was the principal goddess of ancient Egypt, and Isidore was a popular name among the ancient Greeks. There were several saints named Isidore. Isadora is the feminine form.
A baby name that sounds like Isidore is Esdras.